VIP

Also known as Vasoactive intestinal peptide, Aviptadil, Invicorp (with phentolamine), Zyesami

Human trials

Neuropeptide that relaxes smooth muscle and modulates inflammation. Combined with phentolamine it is licensed for erectile dysfunction in some European countries (national approvals); an intravenous trial in COVID-19 respiratory failure showed no benefit.

Not an approved medicine. VIP is not an approved medicine for this use in Australia or the United States. This page summarises published research for information only. It is not a recommendation to use VIP, and VialOwl does not sell or supply it.

Background

28 amino acid neuropeptide first described in 1970 as a blood vessel relaxing hormone from the gut. It is found throughout the nervous system, gut and lungs; the synthetic form is called aviptadil.

How it is thought to work

Binds VPAC receptors to relax smooth muscle in blood vessels, airways and the gut, increase gut secretions and damp down inflammation. In the penis it helps trap blood, which is why it is combined with phentolamine for erectile dysfunction.

What is claimed, and the evidence

Claim	Evidence	Notes
Erectile dysfunction by injection into the penis (with phentolamine, Invicorp)	Small human studies	Licensed in some European countries; supported by clinical studies and a 308 man retrospective series with about 59% success in hard to treat cases. Not approved by TGA or FDA.
Treats COVID-19 respiratory failure	Human trials Not supported	The TESICO randomised trial (461 patients) found no benefit from intravenous aviptadil.
Treats chronic inflammatory response syndrome or mould illness (nasal spray)	No published evidence	Promoted by some practitioners; no published randomised trials found.
Treats pulmonary hypertension, sarcoidosis or autoimmune disease	Small human studies	Small early studies only; not approved.

Side effects

Effect	How often	Notes
Facial flushing	Common	About 22% in the injection series for erectile dysfunction.
Low blood pressure and fast heart rate Serious	Frequency unknown	Expected from its blood vessel relaxing action, especially with intravenous use.
Diarrhoea	Frequency unknown	Very high natural levels (from VIP secreting tumours) cause severe watery diarrhoea.
Priapism (prolonged erection) Serious	Rare	About 0.3% in the injection series.
Serious adverse events in critical illness Serious	Frequency unknown	In TESICO, early serious safety events were numerically higher with aviptadil (63% versus 56%), not statistically significant.

Warnings

Not approved by the TGA or FDA; aviptadil is Schedule 4 in Australia.
Can lower blood pressure; intravenous use should only occur under medical supervision.
Unapproved products are not made to medicine standards and may be contaminated, underdosed, overdosed or contain a different substance from the label; the TGA warns that injected unapproved peptides carry risks including contamination, infection and local tissue damage.

Regulatory status

Australia: Not found on the ARTG. Aviptadil is Schedule 4 in the Poisons Standard.
United States: Not FDA approved (aviptadil). Vasoactive intestinal peptide is in 503A Category 1 (under evaluation for compounding).

Sources

Also in Immune

From the VialOwl library, reviewed 26 September 2026. For education and general information. It is not medical advice and not a recommendation to use VIP.